Buckhorn Plantain (Plantago lanceolata) is a dicot weed in the Plantaginaceae family. In Indiana this weed first evolved resistance to Group O/4 herbicides in 2016 and infests Turf. Group O/4 herbicides are known as Synthetic Auxins (Synthetic auxins (action like indoleacetic acid)). Research has shown that these particular biotypes are resistant to 2,4-D and they may be cross-resistant to other Group O/4 herbicides.

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

Abstract
A population of buckhorn plantain with suspected resistance to 2,4-D was identified in central Indiana following 30 yr of 2,4-D–containing herbicide applications. Our objectives were to (1) confirm and quantify the level of herbicide resistance in the buckhorn plantain population using dose–response experiments and (2) find alternative herbicides that could be used to control this population. Greenhouse experiments were conducted to quantify the dose–response of resistant (R) and susceptible (S) biotypes of buckhorn plantain to both 2,4-D and triclopyr, two synthetic auxin herbicides from different chemical families. The R biotype was ≥6.2 times less sensitive to 2,4-D than the S biotype. The efficacy of triclopyr was similar on both the R and S biotypes of buckhorn plantain, suggesting the absence of cross-resistance to this herbicide. This is the first report of 2,4-D resistance in buckhorn plantain and the first report of 2,4-D resistance in turf. The resistance mechanism was limited to within a chemical family (phenoxycarboxylic acid) and did not occur across all WSSA Group 4 synthetic auxin herbicides, as the pyridinecarboxylic acid herbicides clopyralid and triclopyr and the arylpicolinate herbicide halauxifen-methyl provided control in our experiments.

Greenhouse trials comparing a known susceptible Buckhorn Plantain biotype with this Buckhorn Plantain biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

Genetic studies on Group O/4 resistant Buckhorn Plantain have not been reported to the site. There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature

Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of Group O/4 resistant Buckhorn Plantain from Indiana please update the database.

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Indiana have been instrumental in providing you this information. Particular thanks is given to Aaron Patton for providing detailed information.